Powertrain Systems Description

Computer Inputs and Outputs:

SYSTEM DESCRIPTION:
The Powertrain used in this vehicle consists of a 4.9L dual overhead cam engine mated to a 4T80-E electronically controlled transaxle. It has controls to reduce emissions while maintaining excellant driveablity and fuel economy. The Powertrain Control Module (PCM), is the heart of the control system.

This vehicle uses several electronic components which form an electronic computer network, designed to control various engine and body sub-systems. The heart of the computer network is the PCM. The PCM communicates with the Instrument Panel Cluster (IPC) and the Climate Control Center (CCC) in order to actuate the various on-board diagnostic features of the computer system. The PCM has an internal microprocessor which is the center for communication with all the other components, and controls the on-board diagnostics of the vehicle. All system sensors and switches are monitored by the PCM or one of the other major components that complete the computer system network.

Instrument Panel Cluster:

ON-BOARD DIAGNOSTICS SYSTEM OPERATION
This vehicle is equipped with an extensive on-board diagnostic system which is capable of detecting and compensating for faults, alerting the operator of a fault and recording pertinent data during the failure. It is also capable of displaying information about current vehicle performance when a fault occurred.

In order to access and control the self diagnostics features available, additional electronic components are utilized by the service technician. The Climate Control Center (CCC) provide displays and keyboard switches.

The display and keyboard information is transmitted over a single wire data circuit which carries the coded data messages back and forth between the different control computers. and the display panels Electronic Climate Control Center/Driver Information Center (CCC/DIC). This communications process allows the appropriate computer to transfer any of its available diagnostic information to the appropriate panel for display during service. By depressing appropriate buttons on the CCC, data messages are requested to be displayed on the Fuel Data Center (FDC). the diagnostics mode, the mode indicators on the CCC are used to indicate system operating modes. The different modes of operation are indicated by the status indicator either being turned "ON" or turned "OFF."

SELF-DIAGNOSTICS:
Both the PCM and IPC have the capability to diagnose faults in the sensors, input switches, components and systems they control. When the PCM recognizes a problem, it may turn "ON" the "Service Engine Soon" telltale lamp "ON" the instrument panel to alert the driver that a malfunction has occurred or the PCM may send a message to the IPC to turn "ON" the "Service Vehicle Soon" message on the Driver Information Center (DIC).

SERIAL DATA:
All major components (IPC, CCC, PCM, DIC, etc.) in the system are always in continuous communication with each other to provide accurate control over the many sub-systems involved. When one or more of these sub-system circuits exceeds pre-programmed limits a malfunction is indicated by a service engine soon warning lamp, and a backup function may be activated until the malfunction is corrected. The communications line is a single circuit (CKT 800) which is referred to as the data line or serial data line.